Studies are being conducted to describe the representation of the intrinsic laryngeal muscles in motor cortex of the primate, macaca mulatta. Microstimulation with metal microelectrodes during repeated stereotaxic penetrations in a chronic animal, while observing EMG responses and tensions in various muscles, allow one to map the entire laryngeal motor cortex in a given animal. Besides this knowledge of the myotopic organization of laryngeal motor cortex, experiments should also provide clues as to the role of cortex in laryngeal movements, more specifically, the extent to which cortex is involved in vocalization. The number of representations of each muscle, latency of muscle response to cortical cell stimulation, and nature of this response (e.g., contraction time, peak tension) should help elucidate the role of cortex. Recordings of neural activity during vocalization, obtained during the course of a penetration, should further clarify its laryngeal cortical function. During the conclusion of the terminal study of each animal, tritiated leucine and horseradish peroxidase are pressure injected through the microelectrode at a physiologically defined locus. After an appropriate survival time for transport of tracers, brains are sectioned and treated to neuroanatomically identify projections to and from the physiologically defined site.